Most conventional battery cases for containing the component elements of a battery are metal cases. Various electronic apparatuses including notebook computers and portable telephone sets have been developed and have diffused, and efforts have been made in recent years to reduce the weight and thickness of such electronic apparatuses. Demand for the development of lightweight, thin batteries requiring less space has increased with the progressive reduction in the weight and thickness of such electronic apparatuses.
To meet such a demand, activities have been made for the research and development of various lightweight, thin sheet batteries using electrodes and electrolytes of polymeric materials. Nevertheless, any light, thin battery cases for sheet batteries, satisfying all requisite properties including strength, moisture- and gas-impermeability, sealing performance and adhesion to electrodes and terminals have not been provided.